text: //
  // detail/win_iocp_overlapped_op.hpp
  // ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  //
  // Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
  //
  // Distributed under the Boost Software License, Version 1.0. (See accompanying
  // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
  //
  
  #ifndef BOOST_ASIO_DETAIL_WIN_IOCP_OVERLAPPED_OP_HPP
  #define BOOST_ASIO_DETAIL_WIN_IOCP_OVERLAPPED_OP_HPP
  
  #if defined(_MSC_VER) && (_MSC_VER >= 1200)
  # pragma once
  #endif // defined(_MSC_VER) && (_MSC_VER >= 1200)
  
  #include <boost/asio/detail/config.hpp>
  
  #if defined(BOOST_ASIO_HAS_IOCP)
  
  #include <boost/asio/detail/bind_handler.hpp>
  #include <boost/asio/detail/fenced_block.hpp>
  #include <boost/asio/detail/handler_alloc_helpers.hpp>
  #include <boost/asio/detail/handler_invoke_helpers.hpp>
  #include <boost/asio/detail/handler_work.hpp>
  #include <boost/asio/detail/memory.hpp>
  #include <boost/asio/detail/operation.hpp>
  #include <boost/asio/error.hpp>
  
  #include <boost/asio/detail/push_options.hpp>
  
  namespace boost {
  namespace asio {
  namespace detail {
  
  template <typename Handler, typename IoExecutor>
  class win_iocp_overlapped_op : public operation
  {
  public:
    BOOST_ASIO_DEFINE_HANDLER_PTR(win_iocp_overlapped_op);
  
    win_iocp_overlapped_op(Handler& handler, const IoExecutor& io_ex)
      : operation(&win_iocp_overlapped_op::do_complete),
        handler_(BOOST_ASIO_MOVE_CAST(Handler)(handler)),
        work_(handler_, io_ex)
    {
    }
  
    static void do_complete(void* owner, operation* base,
        const boost::system::error_code& ec, std::size_t bytes_transferred)
    {
      // Take ownership of the operation object.
      win_iocp_overlapped_op* o(static_cast<win_iocp_overlapped_op*>(base));
      ptr p = { boost::asio::detail::addressof(o->handler_), o, o };
  
      BOOST_ASIO_HANDLER_COMPLETION((*o));
  
      // Take ownership of the operation's outstanding work.
      handler_work<Handler, IoExecutor> w(
          BOOST_ASIO_MOVE_CAST2(handler_work<Handler, IoExecutor>)(
            o->work_));
  
      // Make a copy of the handler so that the memory can be deallocated before
      // the upcall is made. Even if we're not about to make an upcall, a
      // sub-object of the handler may be the true owner of the memory associated
      // with the handler. Consequently, a local copy of the handler is required
      // to ensure that any owning sub-object remains valid until after we have
      // deallocated the memory here.
      detail::binder2<Handler, boost::system::error_code, std::size_t>
        handler(o->handler_, ec, bytes_transferred);
      p.h = boost::asio::detail::addressof(handler.handler_);
      p.reset();
  
      // Make the upcall if required.
      if (owner)
      {
        fenced_block b(fenced_block::half);
        BOOST_ASIO_HANDLER_INVOCATION_BEGIN((handler.arg1_, handler.arg2_));
        w.complete(handler, handler.handler_);
        BOOST_ASIO_HANDLER_INVOCATION_END;
      }
    }
  
  private:
    Handler handler_;
    handler_work<Handler, IoExecutor> work_;
  };
  
  } // namespace detail
  } // namespace asio
  } // namespace boost
  
  #include <boost/asio/detail/pop_options.hpp>
  
  #endif // defined(BOOST_ASIO_HAS_IOCP)
  
  #endif // BOOST_ASIO_DETAIL_WIN_IOCP_OVERLAPPED_OP_HPP
  